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Objectives
The objective of this project is to develop a flexible inter-satellite link (FISL) transceiver based on Satlab’s modular transceiver platform. Building upon prior work supported by a national research grant, the project leverages the baseband hardware developed for CubeSat and MicroSat applications, where mass, size, and power constraints are critical. The transceiver design originates from Satlab’s flight-proven SRS-4 S-band module, with over 100 units currently in orbit.
This activity focuses on extending the baseband module with new firmware to enable inter-satellite communication, including message routing and support for relevant waveforms. Additionally, a hardware front-end suitable for half-duplex operation on the S-band is developed. While the primary focus remains on S-band – reflecting current market demand – the design ensures flexibility for adaptation to higher frequency bands, such as X- and K-band, through incremental development.
An EM unit is developed, built, and tested as part of this project. The resulting EM unit serves both as a demonstration platform to engage prospective customers and as a foundation for further investment aimed at achieving a flight-ready product.
Challenges
A key challenge is integrating advanced features like Direct Sequence Spread Spectrum (DSSS) while keeping power consumption low to ensure energy efficiency. The product must also be highly configurable to meet diverse customer needs, yet simple to use and easy to integrate. Striking the right balance between flexibility and usability is crucial. Additionally, fitting all required features into a small form factor without sacrificing performance poses a significant design challenge, requiring careful optimisation of both hardware and system architecture.
System Architecture
The Flexible Inter-Satellite Link (FISL) system features a modular architecture composed of a front-end hardware module, a baseband hardware unit, and configurable firmware. Each module adheres to the PC/104 form factor to ensure compatibility with CubeSat and MicroSat platforms.
The front-end hardware handles signal amplification, filtering, and frequency conversion (up/down mixing) between the S-band (2200–2290 MHz) and intermediate frequencies. It delivers up to 2W TX power, supports RX/TX switching, and maintains a noise figure below 2.5. Selection of critical RF components – especially the power amplifier and switching circuit – is key.
The baseband hardware supports modulation and demodulation across multiple front-end configurations. Its flexible design ensures broad applicability across mission types.
The firmware manages protocol-layer functionality and allows in-orbit configurability of key parameters, including chip rates (100–5000 kcps), DSSS spreading (1–32), error correction (convolutional and Reed-Solomon), and modulation (BPSK/QPSK). Fast signal acquisition is a priority.
The combined system has a form factor similar to the Satlab SRS-4, with a height under 40 mm, total mass below 400 g, and RX power consumption under 2W—ideal for low-SWaP space missions requiring adaptable inter-satellite communication.
Plan
The project is divided into three key phases and associated reviews: The System Requirements Review (SRR), to validate all system requirements, the Mid-Term Review (MTR), to assess design progress and prototype evaluation and the Final Review (FR) to verify the final product against requirements and prepare for delivery. Each milestone ensures the project stays on track and meets its objectives.
Current Status
The project has recently commenced with the kickoff meeting, and is planned for completion in Q2 2026.
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